The present invention relates to a method for manufacturing a magnetic recording medium.
In a conventional method for manufacturing a magnetic recording medium, an underlying film comprising Cr, or Cr alloy such as Cr—V, Cr—Ti, etc. is formed by magnetron sputtering method in part to ensure crystal orientation and particle size control of the recording magnetic film on a very smooth nonmagnetic substrate, and a recording magnetic film comprising CoCrTa, CoCrPt, etc. is formed by magnetron sputtering method on the underlying film, so that an axis of easy magnetization runs in parallel or almost in parallel to the substrate. In addition, as the recording magnetic film, a perpendicular magnetic film comprising Co or Co—Ni having vertical magnetic anisotropy or a vertical magnetizing film comprising Co—Cr formed on a soft magnetic material such as Permalloy film is used. Further, a protective film containing carbon as major component is formed by physical vapor deposition (PVD) method or by chemical vapor deposition (CVD) method based on plasma process.
In the growing process of the carbon film, the difference of deposited particle energy based on the film-forming process is reflected in physical property of the film. For instance, average energy of sputter particles is about 5 eV and a gas used in plasma CVD has thermal motion energy of about 0.03 eV, and hydrocarbon ions are accelerated at several hundreds V. In general, elaborate tetrahedral carbon structure does not grow when low-energy-deposited particles are deposited under low pressure. In particular, in the surface deposition of hydrocarbon radicals, polymerization of polymers occurs. Generally, a PVD method uses ions having energy of about 2 eV to about 10 eV, and a CVD method uses particles having energy of about 0.03 eV.